Ball Valve With Drain 

What is a ball valve with drain? 

A ball valve with drain is a type of ball valve with a tap for releasing excessive or unwanted amounts of fluid from a vessel or pipeline. A ball valve with drain is opened by rotating a handle. When the ball valve with drain is opened, the fluid drains from the vessel due to pressure difference or gravity. Ball valves with drain are designed with perfect seal to ensure it is leakage free. Ball valves with drain are also meant to prevent the build-up of pressure from frosting water when a ball valve is in a closed position. Ball valve with drain helps in line drainage in different applications. Ball valve with drain are used in both heavy duty and light duty applications such as residential and commercial applications. Most of ball valve with drain are made of metallic materials to make them strong for high pressure and high temperature applications.

Figure: Ball valve with drain.

Components of a ball valve with drain 

Valve body 

This is the component of a ball valve with drain used to house internal parts of the valve. The valve body is always made of stronger materials relative to other materials depending on the intended application of the valve. The valve body materials are selected depending on the application pressure and temperatures as well as properties of the fluid like corrosiveness. Some of the materials used to make a strong metallic valve body of a ball valve with drain include stainless steel and brass.

Rotary ball 

This is the component of a ball valve with drain used to close or open fluid flow. The ball has a hole at its center. Fluid flows through the ball valve with drain through this hole when the hole is collinear to the pipe.

Stem

A stem is another component of a ball valve with drain used to transmit the force required to open or close the valve. A stem is a shaft made of strong material enough to withstand the valve’s working pressure and temperature. The stem is used to connect the ball and the handwheel.

Valve drain 

A drain is a port made on the ball valve with drain with a tap. The valve drain is used to drain off fluid from the process line. The tap is used to close or open the valve drain in a ball valve with drain.

Seats

Seats are disc components placed between the valve body and the ball to seal the two components, support the ball, and ensure no fluid leakage.

Packing 

Packing is a seal placed around the stem to prevent fluid leakage.

How does a ball valve with a drain work? 

A ball valve with drain works by using a ball with a hole at its center. The ball on a ball valve is connected to the stem. The stem is then connected to the handle. The ball is responsible for opening and closing the ball valve. To start a ball valve, the handle is rotated for 90^o which then rotates the stem for the same quarter turn angle. With the stem rotated 90^o, the ball also rotates at the same angle of 90^o. This makes the ball hole in line with the pipeline which allows fluid to flow. The ball valve with drain in this state is said to be open or turned on. To close a ball valve with drain, the handle is rotated for the same 90^o in the opposite direction to the direction of opening the valve. This makes the stem and ball rotate to the same angle which makes the ball bore perpendicular to the pipeline and thus fluid cannot flow. In this state, the valve is said to be closed.

Figure: Ball valve with drain showing fluid flow (opened valve) and showing fluid being blocked by the ball (valve closed).

Types of ball valve with drain? 

Two-piece ball valve with drain

A two-piece ball valve with a drain is a valve made of two pieces that is one piece with one end connection, body, and the drain, and another piece with the second end connection. The second piece fits into the first piece to hold the trim in its place. A two-piece ball valve with a drain can be dismantled for inspection, cleaning, and repair and maintenance. However, this ball valve with drain must be removed from the pipeline to separate the two pieces.

Figure: Two-piece ball valve with drain.

Flanged ball valve with drain 

This is a ball valve with drain that has flanged end for connecting the valve to the pipeline using bolts and nuts. This type of ball valve with drain is preferred for its ease of removing because it is just removing the nuts and bolts and then replacing the valve, repairing or inspecting as it may be required. Also, flanged ball valves with drain provide a leakage-free connection when the bolts and nuts are properly tightened.

Figure: Flanged ball valve with drain.

Threaded end ball valve with drain

This is a ball valve with drain that has threads at the end caps for connecting the valve to the pipeline. To use this type of ball valve with drain, then the pipe will need to have threads at the ends so that the two components can be mated perfectly without leakage. One advantage of threaded end ball valves with drain is that they are very common in the market thus making it easy to replace or repair as necessary.

Forged ball valve with drain 

A forged ball valve with a drain is a valve that is manufactured using the forging process. The forging process of making a ball valve with drain involves taking a metallic material and heating it until it is soft and then using mechanical forces like press to shape the material into the required valve. Forged ball valves with drain are known to be strong and free from leakage. These valves are suitable for use in high-pressure and high-temperature applications. Metallic materials that can be used to make a forged ball valve with drain include stainless steel, carbon steel, and brass among others.

Welded ball valve with drain 

This is a ball valve with drain manufactured through the welding method. In this case, the ball valve with drain is welded to connect all the components of the body. One advantage of a fully welded ball valve with drain is that it offers zero leakage. However, a welded ball valve with drain cannot dismantled for checkup. For those welded ball valves with a drain that needs to be cleaned or maintained then the valve needs to be completely removed from the pipe. Welded ball valve with drain needs to undergo non-destructive tests (NDTS) on the welded joints to ensure that they are free from leakage.

Brass ball valve with drain

This is a ball valve with drain made of brass material. Brass is an alloy of zinc and copper. Brass is distinguished by its color which is dull yellowish to reddish based on the amount of zinc used. Brass ball valves with drain are known for being strong, tough, durable, and able to withstand high temperature and pressure. A brass ball valve with drain has good corrosion, chemical, and biofouling resistance. Brass material is malleable which makes manufacturing brass ball valve with drain easier. Also, the brass ball valve with drain is light because brass material is lighter in weight and cheap in cost relative to steel valves.

Stainless steel ball valve with drain

This is a ball valve with drain made of stainless steel material. Stainless steel is a material with high content of chromium and some levels of nickel. Using such elements in stainless steel ball valves with drain makes these valves resistant to corrosion as well as high strength, durability, and toughness despite high temperature and high pressure.

Applications of ball valves with drain 

• Commercial water supply systems.
• Oil and gas supply systems.
• These valves are used in wastewater applications.
• Compressed air systems to remove condensate.

Advantages of ball valves with drain 

• Small in size, unlike other valves.
• Operate quickly when closing or opening fluid flow.
• Light in weight relative to gate valve.
• These valves offer leakage-proof service.
• These valves can be controlled manually with a small force.
• Mostly made of strong metallic materials which makes them suitable for high pressure and high-temperature applications.
• Various types with specific advantages for a user to select a valve that suits their applications.
• Most ball valves with drain are full port ball valves which reduces fluid resistance.
• Versatile as they can be used in different applications.

Disadvantages of ball valves with drain

• Not suitable for throttling applications.
• Some of the these valves such as fully welded and single-piece types cannot be repaired which makes them uneconomical.

Troubleshooting ball valve with drain 

Ball valve with drain having leakage through joints

• Leakage through pipe and valve thread connection. Tighten the connection.
• Leakage through bolts and nuts at the pipe connection. Tighten the bolts and nuts.
• Leakage through the valve joints. Tighten connections for the valve body.
• Damaged or worn out gasket. Replace the gasket.

Leakage through seats 

• Worn-out seats or broken seats. Replace the seats.
• Debris-laden seats. Remove or clean the debris.

Leakage through the ball 

• The ball valve with drain has its ball damaged. Replace the ball. Verify the ball’s compatibility with the media.
• Ball clogged with sediment. Clean the sediment.

Summary 

A ball valve with drain is a type of valve with a tap for releasing unwanted or excessive amounts of fluid from the pipeline. When a ball valve with drain is used to control fluid flow for the main supply it works by rotating the handle for 90^o angle to open or close the fluid flow. The drain port is only used when the excess or unwanted fluid needs to be released. To release the excess fluid, drain tap is turned on to allow fluid flow. These valves are also used to help relieve the pipeline of excess pressure and thus avoid valve or pipe damage.

There are various types of ball valves with drain which include a two-piece ball valve with drain, flanged ball valve with drain, welded ball valve with drain, forged ball valve with drain, brass ball valve with drain, and stainless steel ball valve with drain. Ball valves with drain are used in various applications such as in compressed air, oil and gas, water supply systems in commercial and residential systems among others. Ball valves with drain are advantageous in that they are light in weight, they can withstand high pressure and high temperature, they are cheaper, they are versatile, and they are quick to open/close.